Much effort has been directed to developing methods for treating the various forms of cancer. A number of treatment methods, including radiotherapy or chemotherapy with one or more drugs, toxins, or therapeutic proteins (e.g., interleukin-2) have been developed. Efforts to enhance the patient's immune response to cancer cells (e.g., an antibody-dependent cellular cytotoxicity response) also have been reported. Unfortunately, many of the current therapeutic procedures have met with mixed results, and side effects caused by the action of therapeutic agents on normal cells within the patient's body are associated with many of these procedures. Indeed, the toxic or damaging effect of various therapeutic agents on normal tissues is often the dose-limiting factor during therapy. A need remains for more effective treatments for cancer, especially treatments which minimize side effects caused by action of the therapeutic agents on non-tumor tissues within a patient.